Clogged drains can present an annoying and potentially serious problem. Many different types of material can form or be incorporated into a drain clog, and different types of chemical drain cleaners are known. Some of these chemical drain cleaners are potentially hazardous. The use of pressurized gas to clear clogged drains is also known. Typically, a user will place the outlet of a gas-based drain clearing device against the mouth of the drain to be cleared, and apply pressure to an actuator, which causes a valve to be opened so that the pressurized gas flows into the drain to remove the clog. Typically, the valve will stay open as long as pressure continues to be applied to the actuator, which can result in too much gas being released into the drain, potentially damaging it. One solution to this problem is to provide a single-use cartridge containing a measured amount of gas, but this approach requires the cartridge (or the device, where the cartridge is integral thereto) to be replaced each time the drain clearing device is used. This can be particularly inconvenient for stubborn drain clogs which require more than one burst of gas to be removed.
In addition to drain clearing devices, there are other applications in which metered release of a pressurized fluid is desirable.